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WordPress CVE-2026-1781

MEDIUM
Missing Authorization (CWE-862)
2026-03-11 security@wordfence.com
WordPress Authentication Bypass
6.5
CVSS 3.1 · NVD
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Severity by source

NVD PRIMARY
6.5 MEDIUM
AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L

Primary rating from NVD · only source for this CVE.

CVSS VectorNVD

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L
Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
Low
Availability
Low

Lifecycle Timeline

2
Analysis Generated
Mar 12, 2026 - 22:06 vuln.today
CVE Published
Mar 11, 2026 - 02:16 nvd
MEDIUM 6.5

DescriptionCVE.org

The MC4WP: Mailchimp for WordPress plugin for WordPress is vulnerable to Missing Authorization in all versions up to, and including, 4.11.1. This is due to the plugin trusting the _mc4wp_action POST parameter without validation, allowing unauthenticated attackers to force the form to process unsubscribe actions instead of subscribe actions. This makes it possible for unauthenticated attackers to arbitrarily unsubscribe any email address from the connected Mailchimp audience via the _mc4wp_action parameter, granted they can obtain the form ID (which is publicly exposed in the HTML source).

AnalysisAI

Unauthenticated attackers can arbitrarily unsubscribe email addresses from Mailchimp audiences through the MC4WP: Mailchimp for WordPress plugin (versions up to 4.11.1) by manipulating the unvalidated _mc4wp_action POST parameter, requiring only publicly exposed form IDs. This missing authorization vulnerability allows bulk email removal operations without authentication, impacting any WordPress site using the affected plugin with a connected Mailchimp account. No patch is currently available to address this issue.

Technical ContextAI

Classified as CWE-862 (Missing Authorization). Affects Mailchimp for WordPre. The MC4WP: Mailchimp for WordPress plugin for WordPress is vulnerable to Missing Authorization in all versions up to, and including, 4.11.1. This is due to the plugin trusting the _mc4wp_action POST parameter without validation, allowing unauthenticated attackers to force the form to process unsubscribe actions instead of subscribe actions. This makes it possible for unauthenticated attackers to arbitrarily unsubscribe any email address from the connected Mailchimp audience via the `_mc4wp_act

Affected ProductsAI

Product: Mailchimp for WordPre. Versions: up to 4.11.1..

RemediationAI

Monitor vendor advisories for a patch. Restrict network access to the affected service where possible.

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CVE-2026-1781 vulnerability details – vuln.today
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